This adds fallback implementations for posix_spawn() usage in ntdll and msv1_0. Older Android versions do not provide posix_spawn() or posix_spawnp(). The affected code paths only need simple helper process startup and only distinguish success from failure, so this keeps the existing posix_spawn() implementation where available and uses vfork() with execv()/execvp() otherwise. The ntdll loader path preserves the existing execv-style behavior for a fully built path. The msv1_0 ntlm_auth path preserves the posix_spawnp-style PATH lookup by using execvp() in the fallback. -- v2: msv1_0: Add a fallback for ntlm_auth startup without posix_spawn ntdll: Add a fallback for helper startup without posix_spawn configure: Check for posix_spawn https://gitlab.winehq.org/wine/wine/-/merge_requests/10926